Do I replace a roof that isn't leaking?

[Troy Purvis]

Newbie here! I have my first investment property under contract and have a list of items I will be working on upgrading before renting it out. The roof currently has two layers and IS NOT leaking but does show significant age.  Would you replace the roof now, or wait it out?

I have a couple of bids and it would cost me $5800 to replace.

[Jim S.]

You might be able to wait a couple more years but..... Why would you wait until the roof leaks and does more damage before you replace it?  Do you wait until your tires blow out to replace them???